Method for the manufacture of polyesters
a technology of polyester and polyester, applied in the field of polyester manufacturing, can solve the problems of difficult esterification of dicarboxylic acid ester and terephthala
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example 2
[0044]This example shows a similar reaction as in Example 1, only instead of ethylene glycol (=EG) ethylene glycoldiacetate (=EG-diacetate) was used and no acetic acid or water were employed.
[0045]FIG. 2 shows the HPLC chromatogram, wherein in addition to terephthalic acid (TPA), as another peak terephthalic acid diethylenglycolsterdiacetate (=X1) and peaks at 7 min run time are evident, pointing to the presence of monoethyleneglycolterephthalate (=MGT) and monoethyleneglycolterephthalateacetate. Surprisingly scarcely any diglycolterephthalate (=DGT) was formed, but instead of that various oligomers. This also represents evidence for the acetic acid-terephthalic acid route.
[0046]Benzene was used as internal standard.
example 3
[0047]The following starting quantities were placed in an electrically heated 2 liter autoclave.
[0048]
TABLE 2Water, demin.220 g17.5%Acetic acid415 g32.9%Ethylene glycol485 g38.5%Terephthalic acid140 g11.1%
[0049]The reactor was thoroughly purged with nitrogen before the test began. During the test it was stirred at about 750 rpm. The reactor was heated in under 45 min to 253° C. and then cooled back to room temperature in under 30 min. The analytical results are presented in Table 2A.
[0050]
TABLE 2AinitialTest 1[wt %][wt %]TPA11.14.0Oligomers—13.3EG-—19.5monoacetateEG-—4.5DiacetateDEG——EG38.521.6Acetic acid32.917.6Water17.519.5TOTAL100.0100.0OligomersMGT7.78DGT2.47X12.462GT0.57TOTAL13.3X1 = terephthalic acid diethyleneglycolesterdiacetate2GT = oligomerEG-monoacetate = ethyleneglycol-monoacetate
[0051]Surprisingly in contrast to the conventional terephthalic acid esterification, no diethyleneglycol was formed in the polyester process.
[0052]The conversion of terephthalic acid to ester pr...
example 4
[0054]This example describes the continuous conversion of terephthalic acid and isophthalic acid in acetic acid suspension with ethylene glycol to a polyester product. For this purpose a 1 kg / h ethyleneglycol stream is dosed into a 5 kg / h stream of a saturated solution comprising 70 wt % acetic acid, 25 wt % terephthalic acid, 0.5 wt % isophthalic acid and 4.5 wt % water at a temperature of 200° C. and a pressure of 25 bar and loaded into a first stirred reactor for 60 minutes at 5 bar and a temperature of 250° C. The reaction product was loaded into a second, downstream stirred reactor for reaction at 1.5 bar and 260° C., for 180 min, achieving thereby a conversion of 92%.
[0055]The polyester product was pre-condensed in another reactor and subsequently processed in a polycondensation reactor to a polyester having an intrinsic final viscosity of 0.63 dl / g and carboxyl end-groups content of 20 mmol / kg.
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